All I can do is refer you to the same post on reddit /r/conspiracy. The discussion in that post has a link to the Texas law that allows this. I have not researched it myself, but it appears to check out.
And to answer your question, retirement facilities do not allow people on site without permission. If a poll worker scheduled a visit and asked each person there if they wanted help (on the phone), they would be allowed on the visitor list.
(post is archived)